The Electronika BK was a series of 16-bit PDP-11-compatible Soviet home computers developed by NPO Scientific Center, the leading Soviet microcomputer design team at the time. It was also responsible for the more powerful UKNC and DVK micros. First released in 1985, they were based on the К1801ВМ1 (Soviet LSI-11-compatible CPU) and were the only "official" Soviet home computer design in mass production.
They initially sold for about 600-650 rubles. This was expensive, but marginally affordable, so they became one of the most popular home computer models in the Soviet Union despite numerous problems. Later, when that price edge was eclipsed by cheaper ZX Spectrum clones, their powerful CPU and straightforward, easy to program design made them popular as demo machines. BK (БК) is a Russian abbreviation which stands for "Бытовой Компьютер" -- domestic (or home) computer. It was also for a short time used as cash register, for example, in the State Universal Store.
Although the BK series was included in a governmental economic plan, customer support apparently was not, as it was essentially a barebones machine, without any peripherals or development tools. The only software available at the launch (except ROM firmware) was an included magnetic tape with several programming examples (both for BASIC and FOCAL), and several tests. The ROM firmware included a simple program to enter machine codes, BASIC and FOCAL interpreters.
While the BK was somewhat compatible with larger and more expensive DVK professional model microcomputers and industrial minicomputers like the SM EVM series, its meager 32 KB memory of which only 16 KB was generally available to programmers (an extended memory mode supported 28 KB but limited video output to a quarter of the screen) generally precluded direct use of software for the more powerful machines. Nevertheless, the DVK became a popular development platform for BK software, and when the BK memory was later extended to 128 KB, most DVK software could be used directly with minimal changes.
Homebrew developers quickly filled this niche, porting several development tools from DVK and UKNC. This led to an explosion of homebrew software, from Text editors and databases to operating systems and games. Most BK owners expanded the built-in RAM to at least 64 KB, which not only allowed easier software porting from more "grownup" systems, but as these upgrades often included floppy drive controllers, creating a one's own disk operating system became something of a competitive sport in the BK scene. Games and demo communities also flourished, as its anemic graphics were offset by a powerful CPU.
One of the operating systems was ANDOS, although officially the computer was shipped with OS BK-11, a modification of RT-11.
The machine was based on a powerful (for the time) 16-bit single-chip K1801VM1 CPU, clocked generally at 3 MHz. It was almost perfectly compatible with Digital Equipment Corporation's LSI-11 line, though it lacked EIS and further command set extensions. The manufacturer also closely copied the PDP-11's internal architecture. Each model had one free card slot which was electrically, but not mechanically, compatible with Q-Bus. The first versions had 32 KB onboard DRAM, half of which was used as video memory. That was extended to 128 KB in later models, with video memory extended to two 16 KB pages.
Video output on all models was provided by the K1801VP1-037 VDC, a rather spartan chip. It was actually a standard 600-gate ULA with a VDC program that allowed for two graphic video modes, high-res (512x256, monochrome) and low-res (256x256, 4 colors), and supported hardware vertical scrolling. Later models had 16 hardwired 4-color sets selectable from 64 color palette. It didn't support text modes, but simulated two via BIOS routines: 32x25 and 64x25. Some operating systems such as ANDOS managed to output text in 80x25 mode when displaying documents imported from IBM PC, by placing characters more densely. Output was through two separate 5-pin DIN connectors for a monochrome TV or color TV/monitor. Sound on all models was initially through a simple programmable counter connected to an onboard piezo speaker. Later, the General Instrument AY-3-8910 became a popular aftermarket addition.
All models also had a 16-bit universal parallel port with separate input and output buses for connecting peripherals such as printers (Eastern Bloc printers used the incompatible ИРПР interface instead of the more popular Centronics port, so Centronics printers needed an adapter), mice or Covox DACs for sound output, and tape recorder port for data storage. Later models included a manufacturer-supplied floppy drive controller (that could be plugged into a Q-Bus slot) by default. It was available for earlier models as an aftermarket part, but homebrew ones (that also often extended rather anemic 16K memory of original BK) were more popular. A cottage industry for such peripherals and mods flourished.
Browsing the Collection
There are 30 images for the Elektronika BK-001-411, all of them games.